1 #include "sam.h"
2 
3 static	Block	*blist;
4 
5 #if 0
6 static int
7 tempdisk(void)
8 {
9 	char buf[128];
10 	int i, fd;
11 
12 	snprint(buf, sizeof buf, "/tmp/X%d.%.4ssam", getpid(), getuser());
13 	for(i='A'; i<='Z'; i++){
14 		buf[5] = i;
15 		if(access(buf, AEXIST) == 0)
16 			continue;
17 		fd = create(buf, ORDWR|ORCLOSE|OCEXEC, 0600);
18 		if(fd >= 0)
19 			return fd;
20 	}
21 	return -1;
22 }
23 #else
24 extern int tempdisk(void);
25 #endif
26 
27 Disk*
28 diskinit(void)
29 {
30 	Disk *d;
31 
32 	d = emalloc(sizeof(Disk));
33 	d->fd = tempdisk();
34 	if(d->fd < 0){
35 		fprint(2, "sam: can't create temp file: %r\n");
36 		exits("diskinit");
37 	}
38 	return d;
39 }
40 
41 static
42 uint
43 ntosize(uint n, uint *ip)
44 {
45 	uint size;
46 
47 	if(n > Maxblock)
48 		panic("internal error: ntosize");
49 	size = n;
50 	if(size & (Blockincr-1))
51 		size += Blockincr - (size & (Blockincr-1));
52 	/* last bucket holds blocks of exactly Maxblock */
53 	if(ip)
54 		*ip = size/Blockincr;
55 	return size * sizeof(Rune);
56 }
57 
58 Block*
59 disknewblock(Disk *d, uint n)
60 {
61 	uint i, j, size;
62 	Block *b;
63 
64 	size = ntosize(n, &i);
65 	b = d->free[i];
66 	if(b)
67 		d->free[i] = b->u.next;
68 	else{
69 		/* allocate in chunks to reduce malloc overhead */
70 		if(blist == nil){
71 			blist = emalloc(100*sizeof(Block));
72 			for(j=0; j<100-1; j++)
73 				blist[j].u.next = &blist[j+1];
74 		}
75 		b = blist;
76 		blist = b->u.next;
77 		b->addr = d->addr;
78 		if(d->addr+size < d->addr){
79 			panic("temp file overflow");
80 		}
81 		d->addr += size;
82 	}
83 	b->u.n = n;
84 	return b;
85 }
86 
87 void
88 diskrelease(Disk *d, Block *b)
89 {
90 	uint i;
91 
92 	ntosize(b->u.n, &i);
93 	b->u.next = d->free[i];
94 	d->free[i] = b;
95 }
96 
97 void
98 diskwrite(Disk *d, Block **bp, Rune *r, uint n)
99 {
100 	int size, nsize;
101 	Block *b;
102 
103 	b = *bp;
104 	size = ntosize(b->u.n, nil);
105 	nsize = ntosize(n, nil);
106 	if(size != nsize){
107 		diskrelease(d, b);
108 		b = disknewblock(d, n);
109 		*bp = b;
110 	}
111 	if(pwrite(d->fd, r, n*sizeof(Rune), b->addr) != n*sizeof(Rune))
112 		panic("write error to temp file");
113 	b->u.n = n;
114 }
115 
116 void
117 diskread(Disk *d, Block *b, Rune *r, uint n)
118 {
119 	if(n > b->u.n)
120 		panic("internal error: diskread");
121 
122 	ntosize(b->u.n, nil);	/* called only for sanity check on Maxblock */
123 	if(pread(d->fd, r, n*sizeof(Rune), b->addr) != n*sizeof(Rune))
124 		panic("read error from temp file");
125 }